Skip to main content

Questions tagged [conjunction]

A close approach between two orbiting objects.

Filter by
Sorted by
Tagged with
3 votes
0 answers
65 views

What would be the doppler effect in the a 2.42GHz signal coming from a satellite in orbit around Mars, received on Earth ground station?

Say there is a satellite in orbit around Mars, and it sends a signal at such a time that it is more or less behind the Sun. In that case, Mars would be "Occulted" by the Sun. That signal is ...
Astroquest123's user avatar
1 vote
0 answers
161 views

Issue with propagating TLE sets using SGP4

I am trying to make some analysis on conjunction events using the TLEs available from Celestrak's SOCRATES page. Take for example the following predicted event: Here's my issue: when I try to ...
gio_ros's user avatar
  • 21
0 votes
0 answers
149 views

How does Jonathan McDowell know that Chinese tracking could not possibly have determined a closest approach of 14.5 meters between two space objects?

Space News' Chinese satellite in near miss with Russian ASAT test debris links to the announcement below, and quotes "satellite tracker Jonathan McDowell" poo-pooing the claimed closest ...
uhoh's user avatar
  • 149k
3 votes
1 answer
138 views

Has a cubesat ever caused a problem for another spacecraft? Examples? Close calls?

Cubesats can pose some unique challenges; they are small and so potentially a little harder to track, have larger area/mass so more subject to forces that can change their trajectories, are often less ...
uhoh's user avatar
  • 149k
1 vote
2 answers
136 views

Closest approach between the JWST launch vehicle and Santa Claus's sleigh?

This ABC News video describes how for the 66th year in a row NORAD will be tracking Santa Claus's progress. This year they will have to contend with a potential conjunction between Santa's sleigh and ...
uhoh's user avatar
  • 149k
6 votes
0 answers
96 views

Has there ever been a non-negligible probability of conjunction between spacecrafts in Lunar orbit?

Apparently ISRO's Chandrayaan-2 orbiter and NASA's LRO narrowly avoided a possible conjunction event in Lunar orbit due to timely assessment and action of both agencies. https://www.isro.gov.in/update/...
Ohsin's user avatar
  • 1,812
1 vote
1 answer
180 views

What are these squiggly lines in Jonathan McDowell's tweets about Yunhai-1?

Anton Petrov's new video Another Satellite Collided in Space, But Everyone Missed It Until Now (below) is fun to watch, and links to Jonathan McDowell's tweet string which begins Space-Track catalog ...
uhoh's user avatar
  • 149k
-1 votes
1 answer
93 views

How often does Mars appear at the horizon in our sky? [closed]

How frequently does Mars appear at the horizon in a year(It need not be visible. It just need to be at the horizon)? How long does it take from one of these events to the next one? How long does Mars ...
Writer-at-large's user avatar
24 votes
2 answers
5k views

Is it normal for the US Space Force to warn companies about a possible collision (conjunction)?

I've read a German news article today (Golem.de) stating that there was a conjunction between a Oneweb satellite on its ascension course and a SpaceX satellite. The US Space Force warned Oneweb that ...
Arsenal's user avatar
  • 402
5 votes
1 answer
270 views

What was the relative velocity of Kosmos-2004 and the ChangZheng rocket stage at their closest aproach?

Yesterday (15th October 2020), Kosmos-2004 and a ChangZheng rocket stage were predicted to pass within 25 metres of each other and the media was quick to report the possibility of a collision. They ...
Dave Gremlin's user avatar
  • 2,961
3 votes
1 answer
527 views

What does "MSR" represent in the context of this predicted satellite conjunction?

In a series of four tweets starting with this one (found in 2 satellites will narrowly avoid colliding at 32,800 mph over Pittsburgh on Wednesday) 1/ We are monitoring a close approach event ...
uhoh's user avatar
  • 149k
24 votes
1 answer
5k views

How did two satellites end up in almost the same orbit except moving in opposite directions?

In a series of four tweets starting with this one (found in 2 satellites will narrowly avoid colliding at 32,800 mph over Pittsburgh on Wednesday) 1/ We are monitoring a close approach event ...
uhoh's user avatar
  • 149k
9 votes
2 answers
418 views

Has an astronaut ever seen another object in LEO pass by that wasn't mission-related?

The (currently unanswered) question ISS - Tiangong 2 minimum safe distance suggests that the two space stations passed within about 12 kilometers of each other. @peterh comments that astronauts in one ...
uhoh's user avatar
  • 149k
7 votes
1 answer
228 views

Algorithmic methods or techniques to find conjunctions in large ensembles of state vectors?

Suppose I wanted to answer the question Will Starman/Roadster pass particularly close to any asteroids in the next few years? or try to predict satellite conjunctions around Earth (e.g. Celestrak's ...
uhoh's user avatar
  • 149k
3 votes
1 answer
9k views

Calculating the radial, in-track and cross-track distances

I'm computing the relative distances between satellites. The following picture shows the distances, which are considered as risky. What do Radial, In-track and Cross-track mean and why are they ...
Leeloo's user avatar
  • 703
5 votes
1 answer
397 views

Algorithmic methods or techniques to find conjunctions in high N Keplerian element ensembles?

Suppose I wanted to answer the question Will Starman/Roadster pass particularly close to any asteroids in the next few years? or try to predict satellite conjunctions around Earth (e.g. Celestrak's ...
uhoh's user avatar
  • 149k
2 votes
0 answers
80 views

Will Starman/Roadster pass particularly close to any asteroids in the next few years?

Given what's known about Starman/Roadster's orbit (2018-017A, 43205) have there been, or are there any future predicted close passes to asteroids or comets (or anything) in the next few years? These ...
uhoh's user avatar
  • 149k
8 votes
3 answers
1k views

What is the closest intentional separation achieved by two satellites?

I would like to know what is the closest separation achieved by two satellites. Let's restrict it to Non experimental satellites (or else it would be 0) Operational satellites (no collision) Post ...
Antzi's user avatar
  • 12.7k
4 votes
1 answer
358 views

What is the word for the period between two Mars conjunctions?

Earth and Mars have conjunctions every 15/7 of a year, or every 26 month or every 2 years. And it varies substantially from conjunction to conjunction because of orbital precessions and eccentricities....
LocalFluff's user avatar
5 votes
1 answer
216 views

ISS: Procedure in case of collision warning

In case of collision warning occurring to the ISS, if ISS can't be moved the procedure is to go to a Soyuz and wait. Can anyone gives details about the procedure? Is the Soyuz hermetically closed ...
Antzi's user avatar
  • 12.7k
9 votes
1 answer
1k views

When will 3 outer planets line up for a flyby mission next time?

All 4 outer planets line up once every 175 years. 2 of them line up at least once every orbit Jupiter makes, about every 12 years. But how often do 3 of the outer planets line up? Here's a simple ...
LocalFluff's user avatar
6 votes
1 answer
163 views

Conjunction analysis for deep space missions

How rigorously is conjunction analysis (finding out the chances of hitting an asteroid or another known object) conducted for missions beyond Earth orbit? Due to larger computational resources ...
Deer Hunter's user avatar
  • 11.4k
7 votes
1 answer
237 views

Will Earth, ISS, or Tiangong be the first habitat closest to Juno during Earth Flyby 2013?

Just a fun question (+: Juno is approaching Earth for a gravity assist on her way to Jupiter. Her approach will bring her, at the nearest point, a mere 559KM above Earth's surface. ISS orbits just ...
Everyone's user avatar
  • 13.6k
22 votes
3 answers
1k views

What is the probability of impact?

Space Track is a website dedicated to passing along information about satellites to consumers, primarily satellite operators. The information comes from the US military. In addition to providing the ...
PearsonArtPhoto's user avatar
  • 121k